Finding the least addictive opioid has been a clinical problem almost since these substances -- described by Osler as "God's own medicine" -- entered clinical practice. Very old studies done in prison populations suggest that it's not the chemical identity of the opiate that's the major factor when given in equianalgesic doses, but the route of administration. The more rapidly the drug enters the circulation, the more likely that dependence will develop. In this respect, there's no particular advantage to any of the currently available oral long-acting opiates, and clinicians should monitor patients on therapy with any of these drugs for possible dependence.